North Korea's top military body has accused U.S.-led "hostile forces" of laying siege to the country like Leningrad in World War II and Cuba during the Cold War missile crisis.

In a statement carried Monday by the North's official KCNA news agency, a spokesman for the National Defense Commission (NDC) also said the latest UN sanctions imposed on Pyongyang over its nuclear weapons program were "anachronistic and suicidal" and could trigger a nuclear strike on the U.S. mainland.

The U.N. commissioner who investigated human rights in North Korea on Friday recommended establishing a panel of experts to study how crimes against humanity in the reclusive state can be punished.

"What do you do if we bring home powerful evidence of crimes against humanity -- and a veto" from one of the five permanent members of the United Nations Security Council "prevents you taking it further? How can you deal with that problem?" said Michael Kirby at a conference in London on human rights in North Korea.

The Russian foreign ministry on Monday condemned as "totally unacceptable" North Korea's threats to launch preemptive nuclear strikes against South Korea and the United States, and appealed to all sides to show restraint.

North Korea's threat of "indiscriminate" strikes came just hours before South Korea and the U.S. began annual, large-scale military drills, which usually provoke a hardline response from Pyongyang.

South Korea's parliament on Wednesday passed long-delayed legislation addressing the human rights situation in North Korea -- a move likely to anger Pyongyang with tensions already running high on the divided Korean peninsula.

The bill, first proposed in 2005 but stalled for more than a decade by rival party bickering, has modest aims, including funding for civil activist groups and the creation of an official archive to track and detail rights abuses in the North.

North Korea on Saturday boasted of a newly developed anti-tank weapon that its leader said was so powerful it could turn the most heavily armored enemy tanks into "boiled pumpkin".

Pyongyang's state media said leader Kim Jong-Un had watched tests of the portable, laser-guided rocket and declared it had the "longest firing range in the world", and was "as accurate as a sniper's rifle".

North Korea on Tuesday lashed out at an upcoming joint U.S.-South Korean military exercise, warning it would attack the South and the U.S. mainland in case of any armed provocation.

The South and its close U.S. ally will next month hold their largest-ever annual exercise in response to the North's recent nuclear test and long-range rocket launch, Seoul's defense ministry has announced.

North Korean state media on Sunday confirmed the country has a new military chief following earlier reports in Seoul that the former holder of the post had been executed.

Ri Myong-Su, former People's Security Minister, was referred to as "chief of the Korean People's Army General Staff" when the Korean Central News Agency (KCNA) reported on an army exercise guided by leader Kim Jong-Un.